Low-temperature Superplasticity and High-temperature Tensile Microstructure Evolution of Ti-44Al-6Nb-2Fe Alloy
DONG Shulin1, QU Yingdong1,*, CHEN Ruirun2,*, GUO Jingjie2, WANG Qi2, LI Guanglong1, ZHANG Wei1, YU Bo3
1 School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China 2 School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001, China 3 State Key Laboratory of Light Alloy Casting Technology for High-end Equipment, Shenyang Research Institute of Foundry Co., Ltd., Shenyang 110027, China
Abstract: In order to improve the hot deformation processing capability of high-Nb TiAl based alloys, this study used the Fe element to partly replace the Nb element in high-Nb TiAl based alloys to prepare the new-type high-Nb and Fe-contained Ti-44Al-6Nb-2Fe alloy. The alloy ingot was firstly isothermally package forged, and then the high-temperature tensile testing was carried out on this forged alloy at the initial strain rate of 1×10-4 s-1 and temperatures of 800—1 000 ℃, and the high-temperature tensile deformation behavior and microstructure evolution behavior of the alloy were studied. The results show that the alloy contains more B2 phases(30%—40%). With the increasing of temperature, the dynamic recrystallization effect increases, dislocation decreases, grain size increases, and aspect ratio of grains decreases, all of which correspond to the stress-strain state and enhancement of hot deformation processing capability of the alloy. When the tensile testing is at 800 ℃ and 850 ℃, B2 phase is a brittle phase, and the stress concentration in the regions of B2 phase and B2/γ phase interface leads to the formation of a large number of cracks and holes (14.5% cavity at 800 ℃), resulting in a low elongation (123.1% elongation at 800 ℃), even the early fracture, and the neck shrinkage is obvious. When the tensile testing is at 900 ℃, the strain-rate sensitive exponent m is 0.284, the elongation is significantly increased (163.0%), and the neck shrinkage still exists. When the tensile testing is at 950 ℃ and 1 000 ℃, B2 phase has transformed into a ‘soft’ phase that plays a good role in stress-strain coordination effect, and extensive grain boundary sliding between B2 phase and γ phase can be found. There are almost no cracks and holes in the microstructure, and the elongation increases sharply (307.9% at 950 ℃) without neck shrinkage. The alloy has superplasticity at 950 ℃ and 1 000 ℃, which belongs to low-temperature superplasticity for TiAl based alloys. The higher content of B2 phase and its excellent stress-strain coordination effect are the important reasons and characteristics for the alloy yielding the low-temperature superplasticity.
1 Chen G, Peng Y B, Zheng G, et al. Nature Materials, 2016, 15, 876. 2 Yang G, Tian P J, Ge Z H, et al. Materials Reports, 2020, 34, 08113 (in Chinese). 杨光, 田普建, 葛正浩, 等. 材料导报, 2020, 34, 08113. 3 Zheng G M, Tang B, Zhao S K, et al. Acta Materialia, 2022, 225, 117585. 4 Dong S L, Chen R R, Guo J J, et al. Materials and Design, 2015, 84, 118. 5 Zhang S Z, Kong F T, Chen Y Y, et al. Intermetallics, 2012, 27, 31. 6 Yang J R, Chen R R, Ding H S, et al. Applied Thermal Engineering, 2013, 59, 69. 7 Yang J R, Chen R R, Su Y Q, et al. Energy, 2018, 161, 143. 8 Niu H Z, Tong R L, Chen X J, et al. Materials Science and Engineering A, 2021, 801, 140438. 9 Gao Y L, Kou S Q, Dai J N, et al. Materials Science and Engineering A, 2021, 823, 141772. 10 Guo R Q, Wang X Q, Liu G H, et al. Materials Reports, 2022, 36(S1), 22010111 (in Chinese). 郭瑞琪, 王秀琦, 刘国怀, 等. 材料导报, 2022, 36(S1), 22010111. 11 Song L, Appel F, Wang L, et al. Acta Materialia, 2020, 186, 575. 12 Tan Y M, Fang H Z, Cui H Z, et al. Materials Science and Engineering A, 2020, 797, 140098. 13 Weiss I, Semiatin S L. Materials Science and Engineering A, 1999, 263, 243. 14 Weiss I, Semiatin S L. Materials Science and Engineering A, 1998, 243, 46. 15 Du Z X, He Q W, Chen R R, et al. Journal of Materials Science and Technology, 2022, 104, 183. 16 Sun F S, Cao C X, Kim S E, et al. Metallurgical and Materials Transactions A, 2001, 32A, 1573. 17 Nazarova T I, Imayev V M, Imayev R M, et al. Intermetallics, 2017, 82, 26. 18 Shu S L, Qiu F, Tong C Z, et al. Journal of Alloys and Compounds, 2014, 617, 302. 19 Izumi T, Yoshioka T, Hayashi S, et al. Intermetallics, 2001, 9, 547. 20 Gao S B, Xu X J, Shen Z Z, et al. Materials Science and Engineering A, 2016, 677, 89. 21 Wang Q, Chen R R, Gong X, et al. Intermetallics, 2018, 94, 152. 22 Chen R R, Dong S L, Guo J J, et al. Materials and Design, 2016, 89, 492. 23 Chen R R, Liu Y L, Xue X, et al. Materials Science & Engineering A, 2021, 809, 140912. 24 Zan X, He Y H, Wang Y, et al. Journal of Materials Science, 2010, 45, 6446.
渝公网安备50019002502923号 版权所有：《材料导报》编辑部
2024, Vol. 38 
